Framing light and control for motion-picture machines



Aug. 5, 1952 E. c. MANDERFELD 2,605,673

FRAMING LIGHT AND CONTROL FOR MOTION-PICTURE MACHINES Filed Feb. 17, 1950 5 She eis-Shget 1' INVENTOR. .E/(WAA/UEL cMfl/VDERFELD,

- firraeveys.

Aug. 5, 1952 E. c. MANDERFELD 2,605,573

' FRAMING LIGHT AND CONTROL FOR MOTION-PICTURE MACHINES 1 Filed Feb. 17, 1950 s Sheets-Sheet 2 IIIIIIIII/II/III/II/IIIII/I/III/II/II/I/ i a 6 w [/2 j EMA/0E1. C. MANDEQFELD,

i7? 2 IINVENTOR. waffwfi firraews'ys.

Aug. 5, 1952 E. c; MANDERFELD 7 2,605,573

FRAMING LIGHT AND CONTROL FOR MOTION-PICTURE MACHINES Filed Feb. 17, 1950 5 Sheets-Sheet 3 '1 J51 i 4 jzfyo 40 157 a g; i

I 1 l H Eli/ANUEL C MA/VDBQF'ELD,

INVENTOR.

mizwm,

5, 1952 E. c. MANDERFELD 2,605,673

FRAMING LIGHT AND CONTROL FOR MOTION-PICTURE MACHINES Filed Feb. 17, 1950 5 Sheets-Sheet 4 EifA/W/EL C MA/VDERFELD,

I 1N VEN TOR.

IQTTOQNEYS- Patented Aug. 5, 195 2 1;u"NiT:Eo "SfIfiA-lJEiSL oral-cs 605,673 MING LIGHT; AND. QQ TRQW -MTI ION-PICTURE MACHINES Emanuel Ci -Manderfeld, Los An'gelea- Calif.;-as-

-signor to":Mitchell -(lamera Coi-poratien; Glen idale;-C3Jlifi3n00tfl0fflti0ll of Delaware ApjiliationFebi'flary' 17, 1950, Seria1"No'.'144,6g1

This invention isconcernedgenerally with the problem; ofthreading'fi'lm into "the film feed-i-ng mechanism ofa machinesuchrfor example; as a motion picture "projector. "Standard 35mm. motion "plcture"fi'1m"has four, sets of sprocket holes perpictureirame; and it is-necessary in threading a "projector that the individual sprocket teeth -(or--other-fil-mengaging means) ofthe" filmfeeding mechanism engage the correct holes inthe-film,"so that-the picture frames of the film will register properly with the aperture in thefi'lm gate.

The film advancing mechanism includesanintermittent mechanism the cycle-of operationof whichinclu'des afilm advancing phase and a 'fil-m arresting phase; "When the machine *is-standing stationary with its intermittent mechanism ina position within the fi1madvancing phase of its cycle, the picture iframesj'ofthe filmare' ordinarly" not-registered with the film aperture,-since the film-isthen part way between one frame registering position and the next. The ex-a'ct relation" between-the picture-aperture and the film frames then dependsnpon the exact' phase position of" the intermittent mechanism within the r film moving portion 'of-i'ts cycle;so that it'is difflcultto jpositiorr the film' --correct1y. "-Howev'cr, during" the whole-of thefilm arresting phase of the cycle a film" frame is registered with the aperture. The film can then be correctly placed without regard to the precisemhase position of the intennittent-mechanism*within the *film arresting portion of its' cycle. Hence' in threading a projection "mac'hine the "framing: adjustment is preferably (and, e in" practice; necessarily) performed Withthe intermittent mechanism at-some (largely arbitrary)- p0sition==-within its film 'arresting phase.

" Forthis reason; before-engaging the-fiim-with the' fi-lm moving mechanism, the operator first;

that position. Such locking o'fthe film may be by directflengagement :with the film nioving mechanism, as with a movement of-Gbnevaty ri; or by other means;- siichas the application of friction by closing the gate, as is typically the case with movements of-the claw typei This-'en- 5;

tire operation/referred tot-generally as "fra-ming,

isa necessary andiimportant part of the 'film threading process.

An important objector the present: invention is the simpl ification of framing =by facilitating ther objectis to -insure that-'this sttinQ ofthe machine-is properly-married out before-the operator can complete the -framingprocess;

to-perform *anywspec-ial operations; such as turn ing 011 a 5 light or moving it' from one positionto another. Since-the threading operation -miist sometimes be "performed" as-rap-idly as possible;

the resulting simplification andreliability of'the process which 7 result from' theinvention are-- a very considerableadvantage-'tdtheoperator.

Previously, in preparing I to --establishor as chec'k the frai' nir ig of a film the 'operaterhas ordinarily set the -fi-lrr'nmoving mechanism' to' a film arresting position by turning the machine over manually WithOhe hand-while either Watching the motion 0f "the intermittent sprocket or other film moving 'member) oriee'ling its motion with the other hand. The mechan'is until it I is in a position -W-here the drive shaft can be turned through -a= small' ang le in either direction:withoutaicausing whes rccket-cr ether member to move'. Even if thednachin'e happens to have stopped in a proper framingposition it is generally necessary to check itsposition mate manner: justLdescr-ibed before proceedi ng tefra'me the'fllm.

:According-' to the present inventionthe fra'mihg process is greatl simplified by providing a'ii ih dicating', lsign'al of suitable ty'p'e'g which is oonnected'to. the2film2'moving mehanism in such a wayv that the: signal is actuated- "automatically when the mechanism is at a phase positiemsa fly within the range of its fiIm ar-res'ting -phase. signal actuating mechanism -is preferably-ofsuch a typeithat 'the sig' nal operates When-the-machine is stationary (or is running slowly) -'bu't-' does' not operate when the machine is running at asterm'al operating :speed. I ypical means' fby which this condition is-satisfied are'describd infietail below.

.Many for-ms ofs'ignaP-can-be usd sa asfacme rily, such for example as an audible bell;- operated electrically or mechanic-any. A preferred form of signal wan-cleane- -lam" is-automatically lighted,- --or 'its lightprojction automatically controlled, to indicate correct framing position of 'the mechanism. 'Importantadditional advantages are then obtained, according'to the invention, by using the signal lamp to illuminate the film aperture. Use of the signal lamp also as a framing lamp provides the necessary illumination for adjusting the film without; requiring additional equipment and without requiring the operator to perform any special operation. At the same time it has the great advantage of insuring that the mechanism is properly set before the film is adjusted. Although the operator might occasionally overlook the absence of an auxiliary signal and adjust the film incorrectly because the mechanism was not in a proper framing position, this can scarcely happen when the only adequate light for adjusting the film is obtained by setting the mechanism correctly.

A clear understanding of the invention, and of further objects and advantages thereof, will be had from the following description of a particular illustrative manner of carrying it into effect, together with certain modifications. That description and the accompanying drawings are intended primarily for purposes of illustration, and are not intended as a limitation upon the scope of the invention, The description is based primarily on embodiments of the invention in a projector having an intermittent movement of the Geneva type and utilizing a rotating sprocket as the direct film moving member. However, such embodiment is only illustrative of the invention, which may be applied to other types of intermittent movements (e. g. the claw type) as will be explained. The following description is to be read in conjunction with the accompanying drawings, of which:

Fig. 1 is a schematic elevation, partially cut away in vertical section through the optical axis, showing a typical film aperture and associated mechanism in accordance with the invention;

Fig. 2 is a vertical section at reduced scale taken in aspect opposite to that of Fig. 1;

Fig. 3 is a schematic fragmentary section taken on a plane back of the plane of Fig. 2 in opposite aspect (the same aspect as that of Fig. 1) and at enlarged scale;

Fig. 4 is a fragmentary section, taken as indicated by line 44 of Fig. 1;

Fig. 5 is a schematic drawing illustrating mechanical switch actuating means in accordance with the invention;

Fig. 6 is a schematic drawing illustrating an alternative form of switch actuating means;

Fig. 7 is a fragmentary elevation, in aspect indicated by line 7'! in Fig. 2, and partly broken away;

Fig. 8 is a fragmentary section, corresponding to a portion of Fig. 2 at enlarged scale, and including a schematic diagram of illustrative electrical connections;

Fig. 9 is a fragmentary elevation corresponding to a portion of Fig. 1 and showing a modification;

Figs. 10, 11 and 12 are schematic diagrams illustrating circuitry in accordance with the invention;

Fig. 13 is an end elevation of the machine of Figs. 1-4, taken in the same aspect as Fig. 7, and partially cut away, showing a modification;

Fig. 14 is a vertical section on line |4--I 4 of Fig.

Fig. 15 is a fragmentary section at enlarged scale, in the same aspect as Fig. 13;

Fig. 16 is a fragmentary section on line I5l6 of Fi 15;

Fig. 17 is a perspective of an element of Figs. 13-16; and a Figs. 18 and 19 are schematic perspectives illustrating further modifications of the invention.

In Fig. 1 the optical axis of the projection system is indicated at ID, the light passing from left to right as indicated by the arrow. The film aperture [5 is formed in a removable aperture plate [G which fits in a lateral slot in the face plate l4? of film trap 20, rigidly mounted on a vertical wall I! of the main frame of the machine by means not shown. Film gate 30 is movably mounted, as on rails shown schematically at 3|, for motion generally parallel to optical axis liJ between an open position, shown in Fig. 1, and a closed position in which the rear face 32 of the gate is adjacent the front face 22 of trap 20. When the gate is in closed position, pressure shoes 33, resiliently mounted on the rear face 32 of the gate, cooperate with vertical film channel 23 in the trap, thereby forming a film chute in which the film is frictionally guided past aperture [5. The film is fed between trap 20 and gate 3i) from a continuously movable pull down sprocket, shown schematically at 40, and is pulled past aperture i5 by intermittent sprocket 50, which is mounted on sprocket shaft 5i and is driven by an intermittent mechanism 60 of the Geneva type, shown schematically in Fig. 3, which rotates the sprocket intermittently through an angle of degrees, intervals of such movement alternating with intervals of rest. Each interval of sprocket movement moves the film a distance equal to the frame spacing. The film is taken from sprocket 50 by a continuously movable hold-back sprocket, shown schematically at 41. A sprocket clamp is shown schematically at 53, mounted on the lower end of gate 30 in such a position that it automatically clamps the film to the intermittent sprocket when the gate is closed, and releases the film when the gate is open, Sprocket clamps for sprockets 40 and GI are not shown.

At any convenient point along optical axis l0 one or more shutters are provided, such as the rotating shutters 44 and 45 mounted on shutter shaft 46 (see Fig. 2). Shutters 44 and 45 are operated in such timed relation to the intermittent mechanism, that during the intervals of film movement past aperture I 5 the projection light is out off, but that the light is transmitted during intervals of film rest.

As the film is initially threaded through film channel 23 and over intermittent sprocket 50, gate 38 being open, the sprocket teeth 52 should engage sprocket holes of the film in proper phase relation with respect to the film picture frames so that a film frame will register (at least approximately) with aperture l5 when the sprocket is in a rest position. Such film adjustment is ordinarily accomplished by first setting intermittent sprocket 50 in a rest position (as by turning over the machine manually) and then sliding the film longitudinally in channel 23 until a film frame is observed to be registered with aperture 15. The film is then pressed over sprocket teeth 52 and held in that engaged position until gate 36 is closed, clamping the film to the sprocket by sprocket clamp 53.

It will be convenient now to describe typical driving and control means by which the intermittent mechanism 63 and shutter shaft 46 are operated in correct mutual phase relation, and with correct overall speed relation to continuously movable sprockets 4i! and 4!, while permitting adjustment when necessary of the condition of afra'ming during. operationoffithe machine. Refer "ence is .madeeto Patent2,513;195,;issued:on June 2'7, 1950, to George .A. Mitchell and Emanuel C. Manderfeld, iniwhichv such drivingandrcontrol means are more fullyidescribedandare claimed.

Intermittent sprocket '50on shaft 5Lis-rotated through a 90xdegreeangle inv each successive intermittent movementrby intermittent mechanism .60,-comprising (Fig; 3); a four-sided star cam Bl, :rigidlymounted directly .on sprocketshaft 5 l and engaged. by pin cam 62; which carries pin 63 and is rigidly mounted on pin cam shaft-:Mgparallel to sprocket shaft 5|. Pincamshaft filis .driven from intermittent drivingshaft 10, co-

axial'with sprocket shaft-BL-by the pair of :gears and 12. The three shafts 5l,:-64 and 10,: are j'ournaled inintermittenthousing 15, which in turnis adjustably rotatable aboutthe common axis of shafts 5i and I0. For example,.housing 15 may be journaled in wall I! of the mainframe .of the-machine-by means of cylindrical-surface Jflwhich forms the periphery, of the housing and .is coaxial withshafts 5i. and I0.

;.-Intermittent-driving.shaft I carries: a gear 18 .(Fig. 2) 1by which the intermittent mechanism 50'.is; .driven fromidler gear 80. Gear-801 also .directly engagessprooket driving gears-8l and-83, .Lrigidlymountedon shafts 82 and 84, which carry respectively the two sprocketsdfl and (4| (Fig.1) :A bevel gear 190 .vvhich is pref erably integral with aidler gear-flll; drives shutter shaft-46 .through the train comprising bevelpinion 9] ,jack shaft '93; on :whichxthepinion;isefixed, and thepair of meshed shelicalgears. 95 and 90 .mountedirespectively on @the :jack shaft and the shutter shaft. :Assuming for. purposes of I illustration .that .the shuttersxare designed tomake one.revolutionforeach cycle of filmmovement, and 'that sprockets, M and 50 are 0f equal circumference, the gear ratiosare 'such that" shutter shaft 46 and pin cam shaft 64 aturn four times as fastas sprocket shafts 82. and 84. A driving motor for the. projector is indi'c'ated schematically at: 232 gearedxto sprocket geari83.

If the framing adjustment requires correction during operation of the machine (forwexample, 'because of faulty'initi'al: framing or-as a result of a film imperfection due, e. g. to faultysplicing), this is accomplished by; rotation of-"the' entire intermittent housing15 about the common axis of sprocket: shaft and driving shaft 10, for example bymanually turning shaft I I 00',whichis linked to sector gear IOI -on housing" 15-by idler gear {'02. 'Such rotation of "housing IS-changes the longitudinalposition in film channel I 23 at which the film is arrested betweeniintermittent movements, and-hence-changes the framing ad- "justment. Rotation'of intermittent housing'15 with-respect" to the" main frame of the machine also carriespin camshaft 64 around intermittent driving shaft 10 (to'which it .is linkedbygears 1 l 12) I and. thus changes the phase relation between the intermittent mechanism and the driving gear train, including gears 18' and B0 and shutter jack shaft 93. If that changeof phase between l the intermittent mechanism .and the drivingigearitrain were permittedtoiextend. to ,thejshutter-ishafa.it would..destroy the. shutter timing. g I

:Shutter timing compensationis preferably provided as indicated... at: 2, and asdescribed .more fullyin the above: identified copendingpatrent; application. Helical. gears 85', -90 are -so mounted: as to be. rotationally afixed ,on their re- .--speotive'- shafts but relatively movable -inan axial direction, that relative movement: being under control, of therotational'motion ofyintermittent housing 15. "As. shown, gear 96isrigidly mounted on shutter shaft 46,- and gear 95 is rotationally fixed but axially movable I on ,jack shaft 93; to which his splined at 9 1. The-axial position of gear95 is controlled byyoke '9 8,which is axially threaded to rod 99. That rod is rotationally and slidably journaled, itssliding motion beingdetermined by mesh'of its cylindrical rack teeth I04 (Fig; 3 with gear sector I05 on intermittent housing 15. As housing 15-is ro tated to adjustthe framing,helicalageariq95 is moved axially a corresponding distance. The resulting relative axial movement of the pairof helical gears 95,- -96 produces. relative rotational motion through a definite angle, changing the phase relation between shutter shaft-Hand the inter-mittentdriving gear 18. By appropriate proportioning-of theparts the just described phase shift betweenshutter shaft and-gear 78 can be made to just compensatefor the phase shift described above between gear 18: andthe intermittent mechanism, thus maintaining the required constant-over-all phase relation or timing between the shutter shaft and the intermittent mechanism., independently of rotational adjustment of intermittent housing I5 for-framing. However, with the arrangement here shown,- suchframing-adjustment does alter the phase relation betweenthe intermittent mechanism-and parts of the gear train other -than shutter shaft dii, includin for exam'ple,- idler gear and sprockets 40 and 4|.

vReturning now to the operation of obtaining correct framing ofthe filmwhen threading a film into the machine, the present invention provides, among other things, an improved arrangement for illuminating the film at the film aperture, by which its condition of framing can be judged. The regularprojection light beam cannotbe used as a threading light, since the operation of threadingnecessarily takesiplace-while the machine is not operating. The projection light is then. ordinarilyturned oifand in any cast, the projection lightis thennpurposely cut off from the film aperture by one or more shutters.

'When .thgfilm inlonemachine is nearlyexhausted, a light cut-off shutter, commonly referred to as a dowser shutter, indicated schematicallyat H0 in Fig. 1, is interposed across optical axis [0 (by means notshown) cutting off the projection light of themachine while it is still operating, the dowser shutter of another machine being simultaneously opened. Then, as the first machine comes to a stop,,fire .shutter H2 is also dropped automatically into place behind aperture 15.

. Fire shutter l ILas-shown, is a fiat-metal blade, which slides in vertical guides (not shown), in shutter housing I i3. The upper end of the shutter is flexibly secured as'by hook I I5 to the combinationarm and weight -H6,-which is rigidly connected toashaft lll. Shaft H1 is journaled inv wall I! of themachine frame, and is linked, as indicated in Fig. 2, to a speed responsiv device connectedto the driving mechanismof the machine. As illustrated, a centrifugal governor I20 is mounted. on:shutter shaft 46, outward motion of the governor weights l2l moving groovedcollar I22 to the right in Fig. 2. against spring 123. .Radial-arm I2! is rigidlyrmounted on shaft 11 and is connected-by pivotedlink 1-28 to one end ofelever I-Z S -centrally'piVoted .at .1 26

on frame Wall H. The opposite end of lever I25 carries a yoke I29 which engages grooved collar I22. As the machine reaches normal speed, lever I25 is rotated counterclockwise, turning shaft III clockwise, both as seen in Fig. 2. As seen in Fig. 1, shaft I I! turns counterclockwise, lifting weight II 6 and withdrawing fire shutter blade H2 from the light beam. The design is such that the shutter is snapped open rapidly as the machine approaches normal speed; and is likewise closed rapidly as the machine slows below normal.

The present invention, in the preferred form illustrated, employs the front face of fire shutter I I2 as a reflecting surface against which light is directed at suitable angles by special means to be described, and from which the light is then reflected through film aperture 5 to render the film visible during framing. If dowser shutter IIO were placed in front of fire shutter H2, instead of behind it as shown, it could serve the same purpose equally well; and even in the modification illustrated, dowser shutter IIQ does so serve if for any reason fire shutter II 2 is not closed during framing. Any shutter of similar type that is regularly interposed across optical axis I a short distanc behind aperture I whenever the machine is stationary can act as a refiector for the framing light. No special construction of the movable shutter blade is necessary, a simple reflective surface, such as that iilustrated, being satisfactory for the purpose. This has the advantage of economizing space and simplifying the shutter moving mechanism,

which is particularly important when two or I more closely parallel shutters (such as H0 and I I2) must be operated by separate control means, as is normally the case.

Light is preferably directed against the front face of shutter H2 by special stationary reflecting means placed between the shutter and aperture i5 and closely adjacent the path of the projection light beam. With this arrangement, the light source itself, shown as an electric lamp I 45 in a suitable housing I4I can be conveniently located well away from optical axis It in a position where it is readily accessible and where it does not complicate the necessarily congested arrangement of other apparatus associated with aperture I5. is placed directly below optical axis I5 and slightly behind film trap 25 and intermittent sprocket 50, so that light is emitted in an upward and slightly forward direction into the trap chamber hi5 formed by trap frame I56 and trap face plate I i'I.

In the present preferred embodiment, the framing light is reflected against fire shutter M2 by reflecting shield I50, which is rigidly mounted within trap chamber I45, preferably on the rear face of plate I4? as indicated at I 49. Shield I so has a central aperture I5I, adapted to transmit the projection light beam along axis I0, the edges of the aperture being everywhere as close to axis I0 as is conveniently possible without reducing the intensity of projection illumination at film aperture I5. Thus the light reflecting shield acts also as a heat shield, reducing the intensity of radiation which reaches aperture plate I5 and the portion of trap plate I4! immediately surrounding film aperture 5.

The lower portion I54 of reflector shield :50 is substantially fiat, the main body of the plate being inclined somewhat outward from trap plate I41, bringing the entire upper portion of shield As illustrated, framing lamp 540 8 I50 into spaced relation with its surroundings and facilitating rapid cooling ofthe shield by air circulation through trap chamber I45. The shield sidw are bent back from the general plane of shield aperture I5! to form oblique upper and lower side wings I55 and I56, separated by transverse slots I51, which allow a horizontal bend I58 in the shield proper, midway of its height,-

making the upper portions of the aperture side edges approximately vertical. Those aperture side edges are extended upward as vertical slits I60 above the level of the upper aperture edge (see Fig. 4). The upper part IBI of shield I50 is folded relative to the remainder of the shield about-a horizontal axis I62 through the ends of slits I60. Thus upper part I6I slants upwardly back from trap plate I4! as shown in Fig. 1, extending behind the general plane of shield aperture I 5I above axis I 62, and ahead of that plane below axis I6 I.

Among the advantages of the particular form of shield I50 just described are the large reflecting surface of upper part I6 I, which is slanted at a suitable angle to reflect light most effectively from lamp I toward fire shutter II2; the side wing reflecting surfaces I55 and I56, which similarly direct light toward shutter II2 from each side of axis I 0; and the relatively wide light path between the lower end of shutter housing H3 and lower side I54 of shield I50, permitting free entry of light from lamp I40 into trap chamber I and effective utilization of the reflecting areas just described. Light is reflected first from shield I and then from shutter I I2, for example along the dashed line in Fig. 1, and illuminates aperture I5. An appreciable portion of such light emerges through the opening between trap 20 and open film gate 30, making the film at aperture I5 clearly visible to the operator, and enabling him to judge rapidly and reliably whether the film is properly framed. No special motions on the part of the operator are required to produce this aperture illumination, framing light I40 and reflecting shield I50 being mounted in fixed position, and the fire shutter (or other similar shutter) being automatically moved into position behind the aperture whenever the machine comes to rest.

As pointed out above, intermittent sprocket 50 must be in a rest position when the framing operation is carried out. According to the present invention, such position of the intermittent sprocket is positively indicated to the operator by means now to be described. Any readily perceptible form of signal can be used for this purpose, but it is important for reliable use of such a signal that it does not indicate rest position of the sprocket unless the intermittent mechanism is actually well within the film arresting phase of its cycle, thus giving a comfortable margin of allowable error and assuring reliable results. This is particularly true of visual indication of the sprocket position, which should be of a type which cannot be misread or misinterpreted by the operator.

According to the invention, a positive signal of suitable type is controlled by actuating means directly associated with the intermittent mechanism itself, as distinguished from the intermittent sprocket. That association with the intermittent mechanism may, for example, involve signal actuation directly by some element of the machine mechanism which moves in a definite phase relationship to the intermittent mechanism. Such an element, for example, as already indicated, is the shutter shaft 46, which carries 9 shutters 44 and 45. That'is, rotation of shutter shaft 46' with respect to themain frame of the machine has a. fixed phase relationship to rotation of pin cam shaft 64 with respect to intermittent'housing, 15. In a machine having driving connectionsor intermittent mechanisms of another type, the detailed situation may be different, but the same broad principles will apply.

An important feature of the invention is the indication to the operator of the phase position of .the intermittent mechanism by means of the condition of illumination of the film aperture, so that whenever the film aperture is illuminated the intermittent will automatically be in proper position for framing. This can be accomplished, for example by projecting a beam of lighttoward and through the aperture under controlof a suitable actuating mechanism to transmit the light to the aperture only when the intermittent mechanism is within the film arresting phase. Such an arrangement provides in effect a light source (namely, the light beam) which is energizedunder control of the intermittent mechanism.

An illustrative manner of controlling the aperture illumination to provide a framing indicator is to connect lamp I40 (Fig. 1) in series with a source of voltage, indicated schematically at I88, and with a switch I90. An auxiliary signal, for example an electric bell, may be included in the system, as by connecting it in parallel to framing lamp.I40, as indicated at S. Switch I90 is so actuatedthat the framing light is made to light automatically when the intermittent'mechanism is within a suitable predetermined range of positions within its film arresting phase, illuminating film aperture I5. If the intermittent mechanism is not within that range of positions, and in particular, if the movement is in its film moving phase so that framing should not be attempted, switch I 90 remainsopen and framing light I40 is oil. Hence the operator cannot make the mistake of framing the film when the movement is in incorrect position, since the film aperture is then not illuminated. I

It is preferable, furthermore, .to provide signal'actuating means which are fully operative only whenthe. machine is stationary, or, atleast, only when it is running at less than normal operating speedy An illustrative example of such means for. operating a'switch in'the framing light circuit, such as switch I90 of Fig.1, is shown schematically in Fig. 5. A cam I10 with fiat facel12 is rigidly mounted on a shaft I1 I, which may, for example, be pin cam shaft'64 (Fig. 3) or shutter shaft 46 (Fig. 2). Lever I14, pivoted at I15 is urged by resilient means such as spring I16-into engagement with theperiphery of the cam. Switch contact I18 is so mounted on lever I14 that it contacts fixed contact I19 only when flatcam face I12.is approximately opposite the lever. Thus the switch is-closed when the cam is stationary-within a certain definite range of angularpositions. When shaft vI1I and cam I10 are rotating rapidly, however, the cam remains within thatangular range on each revolution for soshort a timethat the'inertia of lever I14 prevents it from swinging under the influence of spring I16 through the finite angle-necessary to close the switch. By'properly'selecting or adjusting the momentof inertia of lever I14and the torque exerted on the lever by spring I16, the switch maybe-made to remain openat all cam speeds above a selected value.

, An alternative form of switch actuating means inaccordance-with the invention is schematically shown in Fig. 6, corresponding parts in Figs.,5

,andS being similarly'numbered. Cam I10a does not engagelever I14a directly, but acts upon it through resilient-means, typically indicated by spring I0f0-,.mounted on lever I14a and engaging the cam surface, When fully depressed by cam lobe I1 2a spring I is sufficiently stiff to overcome the force of spring I16 and rotatelever I14ato closeswitch contacts I18, I19. However, suchlrotation of lever [14a requires a finite time, because of the moment of inertia of the lever, and the-switch will therefore close only after spring I00 has been held continuously depressed fora definite time, or, in practice, only when cam-l 'lfl is-rotating more slowly than some definite speed. I'he valueof that speed can bedetermined, as before, by proper choice of the physical constantsinvolved. 1

The actuating means shown in both Figs. 5 and 6 can be characterized as time delay-devices,

the delay in those instances being caused pri marily by the inertia of 1 a movable part, lever I14; andaoting to prevent switch closure when the cycle frequency of the control member (cam I10-or' I10a) exceedsa definite value. The preferred phase relation between the switchactuating mechanisms indicated in Figs. 5 and6 and the intermittent mechanism may be visualized by considering that shaft I1I is pincam shaft'64'as shown in Fig, 3, and that the axis of switch ac tuating cam face I12, orof cam lobe Hi l, parallel to that of pin6 3.- Under that condition, lever I14-or I14a-shouldbe oriented withrespect to the shaft as-shownin Figs. 5 and 6.- The switch actuation will then occuronly during-the film, arresting phase of the intermittent cycle, and, in fact, only-during a relatively short portion (determined by the length of the cam dwell) of that film arresting phase. That phase extends throughout theperiod that-pin 63 is disengaged from star cam 6|, about 270 of rotation. By making-the cam dwell appreciably less than that phase angle, and timing the cam as stated above, the period of switch actuation-is notonly less than the period of film rest, but is spaced well within that period in the sense of'both beginning and ending well within the boundaries of the film rest period. U

Another illustrative I form of switch actuating means'is illustrated in Figs. 2 and 7. Switch I90, in the-present instance preferably (as shown) of the typeknown commercially as a microswitch, is mounted on bracket I9I, which also llpports on pivot I92 a switch actuating-lever I93; The inner: end of lever I93 isadaptedto depress actuating' button I 94'- of the microswitch, and its outer end carries a permanent magnet I95} the weight of which normally biases lever I93 against switch closing actuation. An iron shoe-I96 is rigidly mountedas by lugs I91ynear theperiphcry of rear shutter 44 in such a position that-as the shutter rotatesonits shaft 46 the shoe'passes closely above magnet I95, exertingan upward magnetic force of a yielding nature uponthe magnet; and tending 'toxlift itand'swing lever I93 to actuate switch I: Shoe I96 is preferably elongated circumferentially of the shutterpextending-over an angular. range which corresponds to appreciably. lessthan the phaseangle of the film. arresting phase of' intermittent mechanism 60-;- and extending through that portionof the periphery of shutter 44 which is adjacent magnet '-I during -an intermediate portion;- of that phase-of the movement. Whenever the -machine, upon being stopped, comes-to rest-in a' rotational sensitivity to the yielding actuating force.

position which places the intermittent mechanism within that intermediate portion of its rest phase, or whenever, after having been stopped, the machine is turned by hand (as by rotation of knob I93 on shutter shaft 49) to such a position, a part of shoe I96 will lie directly above magnet I95, and will swing lever I93 and close switch I99.

When the machine is in operation the upward magnetic force on magnet I95 acts only during a fraction of each cycle of shutter shaft 46, corresponding to the fraction of the shutter periphery over which shoe I96 extends. By suitably balancing the weight of lever I93 and magnet I95 on pivot I92, or by equivalent means, the upward force on the magnet necessary for switch actuation can be made greater than the average force resulting from the intermittent action of rotating shoe I96, and yet smaller than the continuously acting force when the shutter is at rest in film arresting position. The moment of inertia of the lever-magnet combination about pivot I92 then prevents any appreciable lever movement during the relatively brief individual periods of application of magnetic force when the machine is operating at normal speed. The inertia of the lever and magnet (and similarly the inertia of the lever I'M of Fig. or of lever Il4a of Fig. 6) constitutes a speed responsive means, dependent upon the speed of operation of the machine, since it causes the switch actuating mechanism to respond with differing degrees of At normal machine operation switch operation is completely disabled.

If it is preferred to keep the force required for switch actuation less than the average magnetic force which acts during normal machine operation, switch actuation can be prevented during normal operation by any speed sensitive mechanism associated with the machine and connected to the switch actuating means in such a way as to render the latter inoperative at normal machine speeds, and yet permit switch actuation at low or zero speed. An example of such speed controlled means is illustrated in Fig. 2. Shutter 44 carries near its periphery fan impeller blades 299 which cooperate with shutter housing 29I to deliver a. concentrated air stream through peripheral opening 292 in the housing drawing air through a substantially air tight duct (not shown) between that aperture and the fan, and expelling the air at 292. By mounting a vane, indicated at 293, on the outer end of switch lever I93 in a plane transverse to the exhausted air stream, the magnetic force necessary for switch actuation is made dependent upon the speed of the machine, being unaffected when the machine is at rest and being greatly increased at normal operating speed by the downward force of the air stream on vane 293. Thus, even with a magnet arrangement which gives a very positive switch actuation with the machine at rest, the switch will remain open with the machine in operation. This arrangement is typical of a great variety of speed sensitive devices which can be used to interrupt operation of the switch actuating means when the machine is in normal operation.

a bracket such as I9I in Fig. 2, and is actuated by counterclockwise movement of lever I 93' about its pivot I92, suitably limited by a stop, indicated as a pin 299. Iron shoe I96 is mounted for rotary movement in timed relation to the film movement of the projector, and is illustratively shown, as in Figs. 2 and 7, mounted directly on shutter 44 for rotation with shutter shaft 48. A11 electro-magnet 2I9 is mounted, as on the same bracket ISI, for cooperation with rotating shoe I98. Magnet 2I9 comprises, in the particular form illustrated, an L-shaped yoke of soft iron 2I I, carrying a suitable magnetizing current winding 2I2 on one leg. An elongated armature 2I5, also preferably of soft iron, is mounted on actuating lever I93 and extends freely through an aperture in the other leg of yoke 2II. As shown, armature 2 I5 is longitudinally adjustably mounted on lever I93, and may be locked in adjusted position as by lock nut 2| 5.

Magnet 2I9 and armature 2 I5 are so positioned with relation to shutter 49, as clearly indicated in Fig. 8, that shoe I96 (in certain rotational positions of the shutter) forms a bridge between them, completing a magnetic circuit through yoke 2H and armature 2I5. An electric current in coil 2I2 then produces magnetic flux in that circuit, tending to lift armature 2I5 toward shoe I96 and thereby actuating switch I99. Such switch actuation can occur only when the shutter shaft (and hence the intermittent film movement) is in such position as to bring shoe I 95 opposite magnet 2I9. By suitable proportioning and mounting of the parts, that can be made to occur if, and only if, the intermittent is within some predetermined range of positions within the film arresting phase of its cycle.

The current in coil 2 I2 and the inertia of arma ture 2I5 may be so adjusted that the armature is not appreciably moved, and does not actuate switch I99 whenthe magnetic for e is intermittently applied, as when shutter 44 is rotating at normal speed; but does actuate switch I99 when that same magnetic force is applied steadily, as when the machine is stopped with shoe I96 in switch actuating position. However, in a preferred form of the present modification, means are provided for energizing magnet 2I9 only when the machine is substantially at rest. The magnetic force can then be made relatively great, insuring positive switch actuation under framing conditions, while under normal machine operation, with no current in coil 2I2, the switch actuating mechanism is entirely disabled.

For example, any suitable speed responsive switch may be employed to close a power circuit through coil 2I2 when the machine is at rest, or is substantially at rest, and to open that circuit when the machine is operating substantially at normal speed. Such a switch is indicated schematically in Fig. 8 at 229, connected via lines 223 and 224 in series with coil 2I2 and a suitable power source, represented typically by battery 222. Switch 229 may, for example, be a microswitch, mounted (as indicated in Fig. 9) on wall I! of the machine frame as by a bracket 22'I in such position that governor weight IIB (Fig. l), as it falls to its fire-shutter closing position when the machine is stopped, engages the switch actuating pin, closing the switch and energizing electromagnet 2 I9.

An alternative illustrative arrangement for controlling switch 229 is shown typically in Fig. 10. The main power source for projector motor 232 is represented schematically at 239, conaccuses trolled .in': the usual mannerby "a :motor; switch 234. A normally closed relay, indicated schematically at 236,"v has .its. actuating coil. .connected. inrparallel with. motor '2 3, and "its switch contacts-connected as switch 220 iniF'igs. 8.; The circuit'through coil 2l2 is,thusropenwhenever the main. projector motoris running since relay 236 Lisz-then-actuated, and-isficlosed,"v energizin magnet 21 ll, whenever the. projector; motor circuit is opened to stopth-e-motor and disactuate the. relay; Such'ranarrangement; although. not controlled directly through; the speed of thermachine,..is;actuated.in accordance with the-conditionof operation of the machine, and is included within the :scope .of: theterm speed responsive? asusedin the presentapplicationand claims.

A; further illustrative modification of *suitable meansnior controlling: energization of magnet coil12 I .is shown schematically in-F-ig'l'l. Motor switch .240 isthere shownas :a double pole, double throw switch and is preferably of' the type thatxsnapsxfrom one closed position to the other. Incone closed position of switch 240, powersource 2361s connectedto projector motor 232, operatingv the" projector. Whenever the projector is stopped; switch 2401s thrown to its other closed position, connecting power source 23!) across the lines 223, 224 of Fig. 8, and directly energizing magnet "2H1 in preparation forthe operation of framing. Current source 222 is then not required andJmay.becomittedfromthe circuit of Fig. 8. Fig.) 12 shows a typically alternative manner of connecting. a-switch 24'l-,'of thesametype as 240', whenitis preferred to employ the separate power source: 222 for magnet .energization: Operation of switchZA-l to one closedposition completes a 'circuit'from;main power source 230 through-motor'232s Inthe other c1osed:positi0n0 f switch! that circuit is *opened, stopping the Hinton-and a separate circuit through auxiliary power source 222.and magnet-coil 2l-2.is closed: Circuitry'of the illustrative'types shownin Figs; 11 and '12, like .that of Fig.--l(),-is embracedwithin the term "speed responsive, as. employed herein.

An.alternative'typeof' mechanism forv controlling-a iraminglightsuch-as-l4ll'(Fig. 1) is showndllustratively in' Figs: 13-,1'7. Switch I90 there functionsas acommutator;controlling project-ionoflightfrom lamp .1 40 inaccordance with the phase position ofthe-intermittent; and tisso constructed that the commutator brushes are shifted. out .ofloperating position,-- as by centrifugal.,force,. when. the machine is operating at substantially normal speed.

13..il1ustrates.-a; preferred manner of mountingcommutator contacts. directly onqrear shutter .44 of. theprojector. The shutter, housing. comprises a b0dyportion 245' of shallow cup form. that may bemounted directly onv the rear facev of projector case (0 (Fig; 2) and azflat 'circular. cover portion. 20!. Cover 20 1 is removable bylateral. movement (to the right as. seen in-Fig. 13). in its own plane. Wheninassembledposition its left hand: edge is receivedzby-a 180- degree peripheral channel formed at .246: inthe rim of housing body 245; and a similar.- 180 degree channel 24'! (Fig. 14). formed along; the right handedge of. the cover; receives a radial flange on thehousing. rim. Spring latches, indicated at 249,. releasably secure the cover in. assembled position-by gripping the inner edge ofthe housing rim; A: transparent window. is; removably 'rnountedton cover. 20l at 2 min position to admit light to. the .proj ectore-along optical axisel 0;

Theaparticular. formaof; switch; [96 shownjn Figs; .13-1'1 comprises two mutually; insulated, conductive .rails .2 5.0 'and'22 52;; rigidly mounted as on the.*:inner.;.fixed:i wall .of shutter "housing 245 or directly on the. projector case, in suitableangularrelation to. shutter shaft 46; and two :flex-v ible...contact: fingers-26B and 26:2,.e1ectrically; connectedatogether-and mounted at a suitable posiq tionsonzshutter blade 44.. The ;outer rail edges 25]" have. a: portion: curved circular-1y and, concentrically about the shutter-shaft, and are ,respectively contacted by fingers: 2 6.0. :and 2 62 when theshutteris within-a. particular,;range of angularrpositions: That-contact closes a. circuit be-v tweenzthe itWO grails, providing LSWitCh gactuation.

' As; illustrated; rails $25.0 .and;252 are flat metal stripsaspaced fr-omeach .other and from insulate ing ;-guar.ds*253 rby '3 blocks o'fiinsula'ting. material 254: Those; elements, comprising .rail assembly 251-, .arelsecured together and to the case .wall by two :bolts 2 5 5,2. which; arexinsulated ,from 1 the rails asxby bushings' 256;. Electrical connection to the rails is made in any suitable manner, as by wires 258 soldereddirectly to the rails:

. Spring contact fingers .260 and 262. are typically formed-by: bifurcationof one end .of a strip ofcfiat. spring metal (Fig... 17)., and are preferablyrmounted by securing the'other 'endof that strip to aavmounting block 264- of insulating materi'al,;screwed;or:bolted:to the shutter blade in a. suitably: selected location; as indicated in Figs.

13.?and115. 'Th'efreeends of fingers 260 and 262 carry contact studs. 266, and aresopositioned'that in their equilibrium position the stud .ifacesr lie radially just inside curved rail faces 25l with respect to shutter shaft-'46,:isosthat contact of studs 2661. with rail. edgesv .251 slightly" distorts; the springs; insuringagood electrical contact.

As .=illustr.a-ted;: contact assembly- 261, includes a someansforzdisablin the switch action whenever; the." machine is .not substantially; stationary." A -centrifugalweight 210, mounted on arm 2'H,is-pivoted.at- 212 for limitedswinging movement, along :an :are that extends generally 'radi ally-withv respecttoyshutter shaft 46; A'finger 215, extendingfromarm'fll, is so formed as to engag spring. fingers 260,: 262 and .move *their contactrstu'ds 266 radially outward. from; shutter shait 46-by virtueof centrifugal movement of weight 210, thereby preventing thestuds from engaging rails 250, 252. As illustrated, .finger'2'l5 carries.. an insulating. block 216, which engages theinner faceof the rearwardly curved ends 218 ofrthe-twospring fingers260, 262.

Swinging movement of weight2'l0 is limited radially. outwardly as by a stop 218,. mounted. directly onshutter. 44,- and is. limited radially inwardlyas by stoplug 280 extending from mounting block.264 and. directly engaging finger 215. Those limits. are soarranged that when weight 210 is in its outermost position (typically when the. machine is. operating) finger 2'l5'holds contact studs 266 clear of .rail edges 25l; and that when weight 210 is in its innermost position (typically when the machine is at rest in or near framing position) finger2'l5 permits studs 266 to move radiallyinward sufficiently to firmly engage the rails. Actual rail'contact then typically lifts the ends 218 of" spring fingers 260,262 clear of finger'216 as in Fig. 15, so that the contactpressure isdetermined .entirelyby the stiffness and the relatively small inertia of spring fingers 260, 262;. and isnot affected by the inertia or weight of centrifugal. weight 210. A light springmay be provided,.urging. weight 21 0 radially-inward toward stop 230. However, in the particular arrangement illustrated, it will be noted that when the shutter is at rest in switch closing position gravity tends to swing weight 270 about pivot 212 toward the shutter shaft, making such a spring unnecessary. The weight of the entire contact assembly 23?, including stop 218 (mounted on the primary shutter blade 290), is preferably counterbalanced as by a weight, indicated at 284 in Fig. 13, suitably positioned on the opposite blade 292 of shutter 44.

In the arrangement illustrated, rail assembly 25? and contact assembly 261 are so positioned as to permit switch actuation only during a relatively small portion of the entire film arresting phase of the cycle of the intermittent mechanism. lhat phase lasts typically about 270 of shutter rotation, while the angular extent of contact rails 25!), 252 about the shutter shaft is seen to be only approximately 45. The film moving phase of the intermittent, comprising about 90 of shutter rotation, occurs while primary shutter blade 29B is wholly or partially across the light beam at E0, the shutter blade being typically somewhat less than 90 across, as illustrated. Fig. 13 shows the switch in its actuating phase and indicates clearly that the intermittent mechanism is near the midpoint of its film arresting phase, since flicker blade 292 lies across optical axis I 0. Hence it is clear from the drawings that, with the particular arrangement shown, the period of switch actuation, and hence of framing light energization, is appreciably less than, and is spaced within, the film arresting phase of the intermittent.

A further illustrative embodiment of the invention is shown schematically in Fig. 18. Framing and signal lamp (40 is connected in series with a power source !88 and a switch [90 (as in Fig. 1), the switch here comprising a relay whose magnet coil 298 is energized via an amplifier 380 under control of a light sensitive device, shown as a photoelectric cell 302. Means are provided for projecting a light beam 333 toward photocell 32, such means being represented schematically as a lamp 364 connected in series with a suitable power source 308 and a switch 308. In practice, such projecting means may include also such optical elements as lenses and mirrors, as is well understood in the art.

A shutter is arranged to intercept the light beam selectively in accordance with the phase position of the intermittent movement. Such a shutter may, for example, be an auxiliary shutter disk mounted on shutter shaft 46 of the projector,

and is so shown at 313 in Fig. 18. An aperture 3I2 in disk 310 transmits light to photocell 332 only when the disk, and hence shaft 46, are within a particular range of angular positions, which is made to lie within the film arrestin hase of the intermittent cycle. As illustrated, a shutter arm 3M, pivoted at an eccentric point 3K6 of disk 3H3, is held by spring 3l6 in aperture exposing position (Fig. 18) when the machine is at rest; and is swung radially outward by centrifugal weight 323 against the stop 32! and into aperture covering position (dotted lines in Fig. 18) when the machine is in normal operation. Thus shutter arm 3 E4 cuts off the light beam 333 from photocell 382 in all angular positions of disk 3| 0 during normal operation of the projector. When the projector is stopped in the proper predetermined position for film framing, aperture 312 is uncovered and transmits light beam 303, actuat- 16 ing relay switch 150 and energizing framing light 140.

Centrifugal shutter 3M may be supplemented or replaced by suitable control of lamp 384. For example, switch 308 may represent a speed responsive switch, controlled in suitable manner in accordance with the condition of operation of the machine as typically described above in connection with Fig. 9, for example. Lamp 384 is then energized, and can energize relay coil 298, only when the machine is substantially at rest. Shutter disk 3!!! is to be considered as representative of any suitable means for controlling transmission of light beam 353 in accordance with the phase position of the intermittent movement. It may, for example be replaced by a movable mirror, in such general manner as is described below. And it will be noted that shutter 31!), however constructed, may transmit light beam 303 alternative-1y either when framing light 140 is to be energized (as described above) or when the framing light is to be cut off. In the latter instance, for example, relay switch I90 may be of the normally closed type, closing the circuit through framing lamp I only when coil 298 is energized; or amplifier 380 may be so constructed as to energize relay coil 298 only when photocell 332 is dark.

Fig. 19 illustrates schematically a typical manner in which a movable mirror may be utilized for controlling projection of light directly to the film framing aperture. A similar system may be used, for example, to control projection of light beam 383 in Fig. 18. A typical film aperture is indicated at !5 in aperture plate 22, the axis of the regular film projecting optical system being indicated at 19. Light from framing light H3 is focused into a relatively narrow beam 320 by suitable optical means, indicated as a lens 322. That light beam is reflected obliquely through film aperture [5 by a mirror 324, which is mounted for movement in accordance with the phase of the film intermittent mechanism. As illustratively shown, mirror 324, is a plane mirror mounted by means of disk 326 and clips 328 on a shaft for rotation therewith in a plane normal to the shaft axis. The shaft may be considered to represent typically the shutter shaft of the projector. Mirror 324 is of sector shape, intercepting and reflecting light beam 323 only when shaft 46 is in a certain range of angular positions. The parts are so arranged that such reflection of the beam, causing it to be projected through aperture l5, occurs only when the film intermittent mechanism is in a film arresting phase of its cycle. Although mirror 324 is shown illustratively as a plane mirror, it may have other forms and may thus function to focus the light beam as well as to direct it and control its projection. In particular, the mirror may be a cylindrical or spherical mirror having its axis or center of curvature in the axis of the shaft on which it is mounted. Other optical elements may, of course, be introduced into the system to assist in delivering light to aperture (5 at an effective angle to assist the framing operation.

Particularly in the modification just described, which involves no intermittent mechanical contact of actuating parts, it is not necessary that projection of the framing light be disabled when the machine is in normal operation. However, such disabling action may be provided if desired, as by introducing in the circuit of lamp I40 a switch I30 that is controlled in accordance with the condition of operation of the machine, for example in the manner indicated in Fig. 9.

, The application of the inventionto projector mechanisms of other types than that here illustrated, employing, for example, other kinds of intermittent mechanisms and driving trains, will be obvious to those skilled'in the art. For instance, a projector having a claw type movement may be considered. In that type of intermittent movement the claws are withdrawn from the film race during the rest phase and are projected into the race durin the film moving phase of the cycle; The movement mechanism may have a pilot pin which projects into the race during the rest period to engage a sprocket perforation to register the film position, and which is withdrawn during the film moving period. In threading the film the operator has the same problems as before described; he must register the correct sprocket perforation with'the pilot pin, or place the correct perforation such a position as to be engaged by the claw. As before, itis desirable that either of these operations be performed when the intermittent mechanism is in its rest phase, so that the film can be properly located by framing it at the aperture. The characteristic features of the invention therefore apply regardless of the typeof intermittent mechanism. I

This application is a continuation-in-part of my prior copending application Ser. No. 779,788, filed October 14, 1947, and now abandoned.

I claim:

1. In a motion picture projection machine of the type having a film aperture, a film movin intermittent mechanism for. intermittently moving a film past the aperture, said mechanism having an operating cycle that includes a film moving phase and a film arresting phase, the film arresting phase constituting a definite fraction of theentire cycle, the film moving mechanism normally alternating between said phases at a normal operating speed, and means for illuminating the exposure aperture with a relatively intense projection light beam for projecting an image of a film located at the aperture; a film framing device comprising, a shutter mounted for movement between .an operative position across the projection light'beam in spaced relation to the plane of the aperture and an idle position outside of that beam, framing light projecting means including a light source and means for projecting light of relatively low intensity from the light source through the aperture along a path that is effective for light transmission during presence of the shutter in its operative position, a control for the framing light projecting means having an operating control cycle that includes a framing light projecting phase and a framing light disabling phase, the said framing light projecting phase constituting a definite fraction of the control cycle, which fraction is appreciably smaller than the first said fraction, means for driving the framing light control in definite phase relation to the film moving mechanism with the framing light projecting phase of the framing light control spaced within the film arresting phase of the film moving mechanism, and means responsive to the speed of the film moving mechanism and acting to shift the shutter to its aperture covering position to shield the aperture from the projection light beam when the mechanism speed is appreciably less than normal, whereby aperture illumination with the film moving mechanism at rest can occur only if the mechanism is in condition for film framing.

18 I 2. A film framing device as defined in claim 1, and in which the said framing light projecting means includes a lamp and optical means for projectinga light beam from the lamp through the aperture when the shutter is in operative position, the said optical means including an optical element that is shiftable between beam projecting and beam disabling conditions, and in which the framing light control acts to shift the optical element between its said conditions.

3. A film framing device'as defined in claim 1, and in which'the framing light projecting means includes an electric lamp and electrical circuit means for energizing the lamp, there being a switch in the said circuit means, and in which there is a switch actuating connection between the switch and the said speed responsive means, the said connection acting to close the switch only when the mechanism speed is appreciably less than normal.

4. In a motion picture projection machine of the type having a film aperture, a film moving intermittent mechanism for intermittently moving a film past the aperture, said mechanism having an operating cycle that includes a film moving phase and a film arresting phase, the film arresting phase constituting a definite fraction of the entire cycle, the film moving mechanism normally alternating between said phases at a normal operating speed, and means for illuminating the exposure aperture with a relatively intense projection light beam for projecting an image of a film located at the aperture; a film framing device comprising, a shutter mounted for movement between an operative position across the projection light beam in spacedrelation to the plane of the aperture and an idle position outside of that beam, framing light projecting means including a light source and means for projecting light of relatively low intensity from the light source through the aperture along a path that is efiective'for light transmission during presence of the shutter in its operative position, a control'for the framing light projecting means having an operating control cycle that includes a framing light projecting phase and a framing light disabling phase, the said framing light projecting phase constituting a definite fraction of the control cycle, which fraction is appreciably smaller than the first said fraction, means for driving the framing light control in definite phase relation to the film moving mechanism with the framing light projecting phase of the framing light control spaced within the film arresting phase of the film moving mechanism, means responsive to the speed of the film moving mechanism and acting to shift the shutter to its operative position to shield the aperture from the projection light beam When the mechanism speed is appreciably less than normal, and means actuated in response to substantially normal operation of the film moving mechanism and acting to disable the framing light control to prevent projection of the framing light beam, whereby aperture illumination with the film moving mechanism at rest can occur only if the mechanism is in condition for film framing.

5. A film framing device as defined in claim 4, and in which the framing light projecting means includes an electric lamp and electrical circuit means for energizing the lamp, and in which the framing light control includes a switch connected in the circuit means and comprising a movable switch member and a relatively fixed switch member, the movable switch member being mounted for angular movement about an axis and for movement transversely of that angular movement, a driving connection for driving the movable switch member in its angular movement in definite phase relation to the intermittent mechanism, speed responsive means for driving the movable switch member in its transverse movement in accordance with the speed of its angular movement, one of the switch members having an angular extent about the said axis that is definitely limited and lies within the angle described by the other switch member during the film arresting phase of the operating cycle of the intermittent mechanism, and the relatively fixed switch member having, in the direction of the said transverse movement of the movable switch member, an extent that is definitely limited in such a way as to be transversely spaced from the movable switch member when the latter is rotating at normal speed, and to be transversely contiguous with the movable switch member when the latter is rotating substantially at zero speed.

6. A film framing device as defined in claim 4, and including an element having appreciable inertia and movable between an idle position in which framing light beam projection is disabled and an active position in which the framing light beam is projected, the element being yieldingly urged toward its idle position, and control means for the inertial element comprising a control member movable in a periodic cycle of movement, yielding means shlftable in response to movement of the control member between an active condition in which a yielding force is applied to the inertial element and an idle condition, the

active condition of the yielding means corresponding to a definitely limited range of positions of the control member in its periodic movement, and a driving connection for driving the control member in its said movement in synchronism with the film moving mechanism in such phase relation that the control member passes through the said range of positions during the film arresting phase of the intermittent movement, the said yielding force being of such direction and magnitude as to move the inertial element to its active position when applied continuously, and being insuflicient to move the inertial element to its 20 active position when applied intermittently with the frequency of the normal cyclic operation of the film moving mechanism.

7. A film framing device as defined in claim 4, and in which the framing light projecting means includes an electric lamp and electrical circuit means for energizing the lamp, and in which the framing light control includes a switch connected in the circuit means and including a movable switch actuating element having appreciable inertia, and control means for the inertial element comprising a control member movable in a periodic cycle of movement, yielding means shiftable in response to movement of the control member between an active condition in which a yielding force is applied to the inertial element and an idle condition, the active condition of the yielding means corresponding to a definitely limited range of positions of the control member in its periodic movement, and a driving connection for driving the control member in its said movement in synchronism with the film moving mechanism in such phase relation that the control member passes through the said range of positions during the film arresting phase of the intermittent movement, the said yielding force being of such direction and magnitude as to cause switch actuation when applied continuously and being insufficient to cause switch actuation when applied intermittently with the frequency of the normal cyclic operation of the film moving mechanism.

EMANUEL C. MANDERFELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Addition to NO. 421,659) 

